Post-tensioned anchor device



Jan. 13, 1959 F. H. BRANDT 2, ,8

POST-TENSIONED ANCHOR DEVICE Filed Sept. 7, 1954 2 Sheets-Sheet 1 VAV v v yy INVENTOR. Fred H. Brandt B m ATTORNEYS.

Jan. 13, 1959 F. H. BRANDT 2,857,884

POST-TENSIONED ANCHOR DEVICE Filed Sept. 7, 1954 2 Sheet 2 INVENTOR- 5 Fred H. Br

ATTOR YS United States atent G POST-TENSIONED ANCHOR DEVICE Fred H. Brandt, Kansas City, Mo., assignor to Prestressing, Incorporated, San Antonio, Tex., a corporation of Texas Application September 7, 1954, Serial No. 454,562

4- Claims. (Cl. 251) This invention relates to anchors for post-tensioned members of concrete structures and which are especially adapted for anchoring reinforcing members of the type disclosed in the James J. Mennis application for patent, Serial No. 295,395 filed June 25, 1952.

The reinforcement members of the Mennis application comprise carbon steel wires or small rods having a high elastic limit and provided with upsets or nodules for connecting anchors therewith so that when the wires or rods are post-tensioned and the ends are anchored with the respective sides of the concrete structure, the tension is retained in the members to place the concrete in compression, it being understood that the present invention is directed to the anchor structure per se.

Therefore, the principal objects of the present invention are to provide anchors for engaging upsets or nodules on the ends of the reinforcing members; to provide anchor members for effecting a positive grip on the wires or rods without altering the strength thereof; to provide small, relatively inexpensive anchors which may be readily covered to protect the metal thereof; and to provide anchors having means through which cement may be injected around the reinforcing members.

In accomplishing these and other objects of the invention hereinafter pointed out, I have provided an improved structure, the preferred form of which is illustrated in the accompanying drawings wherein:

Fig. 1 is an end view of an anchor in place for holding tension in reinforcing members.

Fig. 2 is an enlarged longitudinal sectional view showing the anchors fixed to the respective ends of the reinforcing members in a post-tensioned concrete structure.

Fig. 3 is a perspective view of the parts composing one of the anchors, the parts being shown in disassembled spaced relation to better illustrate the construction thereof.

Fig. 4 is a cross section through the anchor at the end to which the pulling force is applied, the section being taken on the line 44 of Fig. 2.

Fig. 5 is a cross section through the anchor at the opposite end on the line 55 of Fig. 2.

Fig. 6 is a side view of one of the reinforcing members showing the nodules thereon.

Referring more in detail to the drawings:

In Figs. 1 and 2, 1 designates a concrete structure having a longitudinal opening 2 extending therethrough for containing a group or bundle of reinforcing members 3. The reinforcing members 3 project from the ends of the openings 2 and are secured by anchors 5 and 6 constructed in accordance with the present invention. The members 5 and 6 engage the ends of the concrete structure to maintain the reinforcing members in tension and that portion of the concrete structure which they reinforce in compression.

After placement and tensioning of the reinforcing members, the opening 2 is preferably filled with a thin cement grout 7 as prescribed by specifications so that they are retain them in the grooves of the socket members.

completely embedded and bonded with the previously formed concrete structure 1.

Each reinforcing member comprises a wire or small rod that is formed of high tensile strength, high carbon steel so that it may be post-tensioned and the tension retained throughout the life of the structure. The reinforcing members are of an initial length relative to the length of the reinforced portion of the concrete structure to provide the required tension and leave projecting ends for connection with the anchor 5 and permit connection of the other ends with a hydraulic jack (not shown) by which the members are post-tensioned, and permit connection of the anchor 6.

To facilitate a positive connection of the anchors and the hydraulic jack with the reinforcing members without marring, scoring or otherwise deforming the reinforcing members, one end of each reinforcing member is provided with a nodule 9 and the other end with spaced nodules 1011. The nodules may have been formed on the wires or rods by upsetting portions of the rods after the rods or wires have been drawn and cut to the desired lengths. When thus formed, the nodules constitute an integral part of the wires or rods and permit connection of the anchors as well as the hydraulic jack without any injury to the reinforcing members. i

The anchor members 5 and 6 which constitute the present invention cooperate with the nodules on the reinforcing members in making positive connections between the reinforcing members and the concrete structure. The anchor members 5 and 6 seat on plates 13 and 14 which bear against opposite faces of the concrete struc ture and have openings 15 and 16 to pass the ends of the reinforcing members and are of exterior size to provide the desired bearing contact with the concrete structure 1 and to distribute the forces resulting from posttensioning of the reinforcing members.

The opening 16 in the plate 14 is ofa size to pass the nodules 10 and 11 but the opening 15 in the plate member 13 is of smaller diameter to encircle closely the body portions of the reinforcing members 3. v

The invention also contemplates a key member 17 formed of plate sections 18 and 19 having semi-circular notches 20 in abutting edges 21 and 22 thereof to form an opening 23 corresponding in diameter to the opening 15 in the plate member 13.

The anchor members 5 and 6 include collars or socket members 24 and 25 of sufiiciently large diameter so that end faces 26 thereof seat against the bearing plate member 13 and key member 17 respectivelywhen the socket members 24 and 25 are placed over the ends of the reinforcing members as shown in Fig. 2. The inner annular faces 27 of the socket members have substantially longitudinal grooves 28 of substantially semi-circular cross section to receive therein substantially one-half the diameter of the respective reinforcing members 3. The socket members 24 and 25 have internal annular flanges 29 that are provided with notches 30 registering with the grooves 28 (Fig. 3).

Received within the socket members 24 and 25 and bearing against the inner side faces or shoulders 31 that are formed by the flanges 29, are core members 32 and 33 each having cylindrical body portions 34, having grooves 35 which are adapted to register with the grooves 28 to engage and spread the reinforcing members and The anchors also include core members 36 and 37 which may have truncated body portions 38 and flat-sided flanges 39 at base portions thereof. The flat sides 40 of the members 36 and 37 may have notches 41;also registering with the grooves 28 of the socket members 24 and 25 to cooperate in retaining the reinforcing members in circumferentially spaced relation and to prevent turning of the core members 34 and 35, when the parts are to be clamped together as later described.

f when' endface sf42 of: the core m'embers 3 2-and=33 are seated upon the shoulders 31, the opp'osite" faces 43 of the core members cooperate with outer annular faces 44 of the collar members '24 and '25" in forming. abutments for the nodules ofthereinforcementmeinbers as later described. 5

The anchor member 6 also includes a washer 45 having-an outermarginalportion 45- that laps the opposite sides of the 'nodules 10as shown in Figs. 1 and 2. The washer 45 has an axial opening 46 registering with an axial open'ing '47' in'th'e outerc'ore member 33'and' an internally threaded axial opening 48" extending axially through the inner core member 37 so that the core member'sSS-ahd'B-Y may be'secured together by a nipple The nipple 49 extends-through the registering openings 46- and" 47 and has a threaded erid'ESi) engaged in'the threaded op enirig48. The opposite end 51 of the nipple projects through the Washer 47 and is externally threaded to mount anut,52 to make a connection with pressure duct (not shown) to supply the cement grout-7.

The core members 32 and the core member 36 of the anchor 5 have a similar opening 53 and a threaded opening 54 respectively toaccommodate a similar nipple 55 and which has an outer'threaded end 56 for a nut 57 i which operates to hold the parts of the anchor 5 together. The nipple 55 also projects beyond the nut 57 to accommodate an internally threaded closure cap 58 to stop the flow of'cement'grout therethrough as later described.

,As'sumih'g thatthe' concrete forming the structure 1 has cured, the rods are gathered in a bundle. The plate member 13' is passed over the'bundle of rods 3. The collar 24 isslip'ped over the end of the nodules 9 and moved back on the rods so that the nodules 9 can be spread sufliciently to permit insertion of the core members 36 and 32. The nipple 55 is inserted through the core member 32 and threaded'into the coremember 36. Then the collar member is brought back along'the rods 3 to bear against the nodules 9 and to seat the core members 36 against the member 32 by applying the nuts '57 to the outer end of the nipple 55.

The corresponding parts of the anchor 6 are applied in like manner under the nodules 10 of the rods 3. The entire assembly is slipped through the opening 2 thathas been provided'in the concrete member. The rod assembly including the anchor 5 is pulled up to the bearing plate .13 and the bearing plate 13 against the con'crete structure; The bearing plate 14 is then applied over the anchor 6 and seated against the opposite side of the concrete structure;

The jack (not shown) is then brought into position with the feet thereof resting against the end of the concrete structure and the actuating member thereof is engaged with the nodules 11.

Since the opposite ends of the reinforcing members have been secured by the'anchor 5, operation of the jack will stretch the reinforcing members sufliciently to elongate the rods 3 and provide clearance for inserting the key member 17 which consists of the parts 18 and 19, after which the pressure of the hydraulic jack is relieved to allow the collar member 25 to seat against the key member 17 and the key member 17 against the bearing plate 14. The jack may then be released and moved, after which the projecting ends of the rods carrying the outer nodules 11 are removed at a given distance ahead of the nodules 10. If desired the washer and nuts 52 and-57 may be removed after post tensioning. The cement grout 7 may be forced through the nipple 49 and in around the reinforcing members 3 to fill the opening 2, the air escaping through the open nipple 55. When the grout begins to flow from the nipple the cap 58 may be. applied to build up pressure on the grout to assure 4 complete filling of the opening..2,-so that the tensi'oned reinforcing members are securely bedded in the concrete structure.

From the foregoing, it is obvious that I have provided secure and safe anchors for the reinforcing members and that the anchors are readily applied and engaged with the nodules thereof to retain tension in the reinforcing members.

After the anchors are in place, the projecting parts, which include the anchors, are relatively small and therefore require a relatively small amount of concrete or cement to cover the metal parts. The amount of covering materialrequired to encase the exposed'ends of the anchors is so small that it does not affect the design elements of the concrete structure.

What I claim and desire to secure by Letters Patent is:

1. An anchor for reinforcing members having nodules on an end thereof, said anchor including a collar member having longitudinal-grooves for accommodating the reinforcing'members, acore member having seated support in the collar member for retaining the reinforcing members in said grooves, a complimentary core member engaging the collar member in opposite relation with the first named core member, saidcomplimentary core member having a'threa'ded axial opening registering with an axial opening in said other core member, an externally threaded nipple having one' end engaging the threads of the complimentary core member and extending through the opening of said other core member, and a nut on the nipple engaging'said' other core member to draw said members together for retaining the reinforcing members in said grooves.

2. An anchor for reinforcing members having nodules on an end thereof, said anchor including a collar mem her having longitudinal grooves for accommodating the reinforcing members, a core member having seated support in the collar member for retaining the reinforcing members in said grooves, a complimentary core member engaging the collar member in opposite relation with the first named core member, said complimentary core mem ber having a threaded axial opening registering with an axial opening in said other core member, an externally threaded nipple having one end engaging the threads of the complimentary core member' and extending through the opening of said other core member, and a nut on the nipple engaging said other core member to draw said members together for retaining the reinforcing member in said grooves, said nipple forming a-passageway through said anchor and means closing said passageway.

.3. An anchor for reinforcing members having nodules on an end thereof, said anchor including a collar member having longitudinal grooves for accommodating the reinforcing. members, a core member having seated support in the collar member for retaining the reinforcing members in said grooves, a complimentary core member engaging the collar member in opposite relation with the first named core member, said complimentary core member having a threaded axial opening registering with an axial opening in said other core member, an externally threaded nipple having one end engaging the threads of the complimentary core member and extending through the opening of said other core member, a nut on the nipple engaging said other core member to draw said members together for retaining the reinforcing member in said grooves, and a washer between the nut and said other core member for cooperating with the collar member in clamping the nodules therebetween.

4. An anchor for reinforcing members having nodules on an end thereof, said anchor including a collar member having longitudinal grooves for accommodating the reinforcing members, a core member having seated support in the collar member for retaining the reinforcing members in said grooves, a complimentary core member engaging the collar member in opposite relation with the first named core member, said complimentary core member having a threaded axial opening registering with an axial opening in said other core member, an externally threaded nipple having one end engaging the threads of the complimentary core member and extending through the opening of said other core member, a nut on the nipple engaging said other core member to draw said members together for retaining the reinforcing member in said grooves, a washer between the nut and said other core member for cooperating with the collar member in clamping the nodules therebetween, said nipple forming a passageway through the anchor, and means for closing said passageway.

References Cited in the file of this patent UNITED STATES PATENTS Hotz June 26,

Wiedenbeck June 20,

Parry Sept. 9,

FOREIGN PATENTS France Apr. 9,

France Oct. 31,

Great Britain Sept. 6,

Great Britain 

